It is often required to attach components to hollow core panels. Such panels may comprise a light-weight core of metal or plastic honeycomb, foam plastic, or balsa wood, for example, which is sandwiched between two outer skins of any desired material, such as wood, metal or plastic. These hollow core panels have very high strength for their weight and have many applications where weight considerations are important.
Fastening a component to a hollow core panel requires utilizing special inserts that are inserted into the panel from opposite sides and are configured to distribute shear loads into the outer skins of the panel. This is accomplished by large area heads or flanges on the insert which are glued to the outer skin and are of sufficient area to distribute shear loads to the outer skin. In the case of threaded inserts, the portion of the insert passing through the panel core is of sufficient size to carry the compression load of the tightened mounting screw to thereby prevent local compressive crushing of the hollow core panel.
In order to obtain the maximum load transfer from the insert flange to the panel skin it is necessary to position the flange away from the skin at a distance equal to the optimum adhesive thickness. If the thickness of the adhesive is greater or less than the optimum the strength of the bond between the insert and skin will be significantly degraded.